Most prior art water quality monitoring systems rely on discrete field sampling followed by laboratory analysis. Frequent chemical testing is expensive. Continuous chemical monitoring systems have not been developed because of the need for expensive, sophisticated instrumentation and highly skilled technicians to operate, calibrate and maintain the system. Furthermore chemical testing is limited by the specificity of the parameters being tested.
On the other hand, monitoring properly selected living organisms which are exposed to the water being monitored automatically detects a wide range of conditions which affect water quality. Such testing is not limited by the specification of a preselected set of parameters to be tested, because any pollutant or environmental condition which causes the organisms to move abnormally will be detected. Also such testing automatically yields an indication of the level of significance of an environmental perturbation in the form of the degree of abnormality of the organisms' movements. Dead organisms clearly indicate a more severe condition than mildly excited or mildly sluggish organisms.
While there is currently no commercial product available that continuously monitors water quality, the relevant literature describes a variety of experimental systems which monitor living organisms in order to monitor water quality. The most relevant literature is as follows: W. H. van der Schalie, Utilization of Aquatic Organisms for Continuously Monitoring the Toxicity of Industrial Waste Effluents, paper no. 22, Technical Defense Information Center 5100.36 (1981); K. S. Lubinski, et al., Microprocessor-Based Interface Converts Video Signals for Object Tracking, Computer Design, pp 81-87 (December 1977); K. S. Lubinski, et al., Effects of Abrupt Sublethal Gradients of Ammonium Chloride on the Activity Level, Turning, and Preference-Avoidance Behavior of Bluegills, Aquatic Toxicology, ASTM STP 707, pp 328-340 (1978); J. Cairns, Jr., et al., A Comparison of Methods and Instrumentation of Biological Early Warning Systems, Water Resources Bulletin, vol 16, no. 2, pp 261-266 (April 1980); W. S. G. Morgan, Biomonitoring with Fish: an Aid to Industrial Effluent and Surface Water Quality Control, Prog. Wat. Tech., vol 9, pp 703-711, Pergamon Press (1977); H. Kleerekoper, Some Monitoring and Analytical Techniques for the Study of Locomotor Responses of Fish to Environmental Variables, Biological Monitoring of Water and Effluent Quality, ASTM STP 607, pp 110-120 (1977); and C. L. M. Poels, An Automatic System for Rapid Detection of Acute High Concentrations of Toxic Substances in Surface Water Using Trout, Biological Monitoring of Water and Effluent Quality, ASTM STP 607, pp 85-95 (1977). Note that "ASTM" is an abbreviation for American Society for Testing and Materials, and "STP" is an abbreviation for Special Technical Publication.
All but one of the systems described in the literature and known to the inventors use non-video techniques for monitoring a living organism. See above cited articles by K. S. Lubinski. Most systems monitor either the breathing response of fish or use photocells to monitor their ability to maintain their position in a flowing stream of water. Video-based monitoring systems, however, have numerous advantages over types of known monitoring systems, once the problems associated with handling the large quantities of video data that are generated by a video camera have been surmounted.
All the known prior art systems monitor the health of a single fish per tank. This tends to make the system highly susceptible to idiosyncratic behavior by a single relatively intelligent organism. It also makes the system dependent on a small statistical base. But most importantly, these prior art systems could not measure interactions between organisms. The inventors have discovered that interactions between organisms, such as schooling behavior, are in some instances more sensitive to stress that other observables.
Similarly, all known prior art systems used large test organisms (i.e., fish). In most cases, the prior art system measured electrical impulses generated by the breathing of the test organisms. The need for electrical signals greater than the background noise dictated the use of large test organisms. Also, these prior art systems generally measured only one parameter, such as breathing rate, which greatly limited the ability of the system to detect stress.
It is therefore an object of the invention to provide an improved water quality early warning system which uses video techniques to monitor the movements of a plurality of living organisms.
Another object of the invention is to provide a system capable of continually or periodically monitoring water quality.
Another object of the invention is to provide a system which accommodates normal seasonal variations in water quality and normal cyclical changes in animal behavior.
Yet another object of the invention is to provide a reliable system which is basically self-operating, requires only occasional periodic maintenance, and can be produced at a low enough cost to make its use in most drinking water supply systems for medium or large populations financially justifiable.
Still another object of the invention is to provide a system which automatically updates its knowledge base and refines a comparative behavior model.